If you want to use 64 bit or newer version, you can change CCX executable with bconverged.com free version. New 64 bit versions can have troubles, you can use the old stable realize from here http://dwg.ru/dnl/12352
Download and install it with desirable options. Go to the program folder and find ccx.exe
You can't replace CGX executable !CalculiXForWin supports:
1. Units and default material;
2. Fast dealing with groups
3. Applying boundary conditions and step options via interface.
and much more...

This is not 100% true. If you need to solve little problem, that is not typical for you (for example thermal analysis at structural engineering) - you don't need to buy full Ansys or Nastran for that (which can be more expensive than you current order). But if you're doing structural work every day - you will need professional software. Free software is the supplement and not a replacement

there is more, if programming becomes like pharmacy today, its bad. some one has a problem and want to do some engineering and he can only go to the software companies which sell at high prices, that is bad. think about, poor country's where a engineer wants to solve complex problems. And also copying data doesn't cost, so why do those company's do ask ridiculous prices.PS: last video of ball and plate. super! want to try it my self